On Thu, Dec 21, 2017 at 10:58:38AM +0000, Chris Wilson wrote: > Quoting Du, Changbin (2017-12-21 09:52:16) > > Hi Chris, > > Our QA reported a problem caused by movntdqa instructions. Currently, the KVM > > hypervisor doesn't support VEX-prefix instructions emulation. If users passthrough > > a GPU to guest with vfio option 'x-no-mmap=on', then all access to the BARs will > > be trapped and emulated. The KVM hypervisor would raise an inertal error to qemu > > which cause the guest killed. (Since 'movntdqa' ins is not supported.) > > > > One possible solution is that disable this optimization at i915_memcpy_init_early. > > This require us to identify the CPUID to check if it is running in guest mode. > > But do note we are already checking the CPUID/cpuflags for support; is > the hv not correcting them? > -Chris The CPU does support SSE, but just the KVM ins emulator doesn't. So it is not a problem if the movntdqa runs on HW directly. But if it is emulated, then run into failure. -- Thanks, Changbin Du _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
